1. Field of the Invention
The present invention relates generally to a spray nozzle, and more particularly, but not by way of limitation, to an improved spray nozzle that is constructed to remain substantially clog free and an improved method of using a spray nozzle to zone water loading within the cooling tower and thereby balance the air to water mixture of the cooling tower.
2. Brief Description of Related Art
Cooling towers typically utilize a grid work of overhead nozzles to form a plurality of overlapping spray patterns for the purpose of distributing water over the upper surface of a layer of fill material through which air is drawn. The water flows downward through the fill material as the air flows upward through or across the fill material whereby the heat of the water is transferred to the air.
It is important to obtain as uniform a distribution as possible of the water over the upper surface of the fill material so that the water will uniformly flow through the fill material across the entire cross-sectional area of the tower. If the water distribution is not uniform, channels of uneven water loading will develop which cause the formation of low pressure paths through which the air will channel, thus greatly reducing the efficiency of the heat exchange operation conducted by the cooling tower.
It has been found that the efficiency of the heat exchange operation is greatly increased by using fluid distributing devices or nozzles that will create a plurality of abutting or overlapping square spray patterns, such as that disclosed in U.S. Pat. No. 5,152,458, the entire contents of which are hereby incorporated herein by reference. The formation of square spray patterns enables the spray patterns to be mated with each other so that voids or gaps do not exist between adjacent spray patterns. However, inefficiencies may still occur if the fluid distributed by each nozzle is not distributed uniformly across each of the individual square spray patterns.
The nozzles typically include a nozzle body, a cap, and a turbine. The nozzle body is provided with a central hub fixed within a fluid passage of the nozzle body with a plurality of radially spaced ribs. The cap has a stem with a central bore. The stem is configured to be slidingly registered in the central hub of the nozzle body. The cap is connected to the nozzle body so that the nozzle body and the cap are spaced apart from one another to define an annular nozzle opening therebetween.
The turbine has a mounting ring sized to be positioned about the nozzle body, a plurality of fins extending circumferentially about a bottom surface of the nozzle body, and a plurality of guide tabs extending radially inwardly of the mounting ring for maintaining the fins in an operable relationship with the nozzle opening. The fins extend radially outward from the bottom surface of the mounting ring so that the fins are positioned to intercept the fluid exiting the nozzle opening and uniformly distribute the water. The guide tabs are sized and shaped to be positioned in the nozzle opening so that the turbine is freely rotatable between the nozzle body and the cap. The guide tabs are generally flat so that a portion of the fluid in the nozzle opening flows across the top of the guide tab while another portion of the fluid flows across the bottom side of the guide tab. The flow of fluid across the guide tabs in this manner creates a fluid bearing on which the guide tabs and in turn the turbine rotate.
While such nozzles have met with success, drawbacks nevertheless are encountered. In particular, such cooling tower nozzles are subject to failure as a result of debris clogging the nozzle and solids accumulating on the guide tabs. Cooling tower water often contains debris, such as twigs and plastic bags, and solid particulate matter. The debris will often catch on the central hub of the nozzle body and/or the radial ribs that support the central hub, thereby clogging the nozzle. In addition, sludge can build up on the guide tabs thereby increasing the weight of the turbine and thus increasing the friction between the guide tabs and the cap which in turn results in premature failure of the guide tabs.
To this end, a need exists for a spray nozzle which overcomes the problems of the prior art. It is to such a spray nozzle that the present invention is directed.